Facebook and Cambridge Analytica should fully comply with investigations into "very concerning" claims about the harvesting of personal data, Prime Minister Theresa May told the Commons.
Her comments come after the Information Commissioner's Office confirmed it was investigating the allegations.
Mrs May said: "I would expect Facebook, Cambridge Analytica and all organisations involved to comply fully with the investigation that is taking place."
Cambridge University psychologist Aleksandr Kogan, who developed the app used to gather data for the research firm, told the BBC's Today programme he would be prepared to appear before Parliament or the US Congress to give his version of events.
He claims both sides are using him as a "scapegoat" in the row and says he believed what he was doing was "perfectly legal".
He claimed CA approached him to do the work, which resulted in the details of around 30 million Americans being collected, but he did not know how that information was used by the data firm.
"My view is that I'm being basically used as a scapegoat by both Facebook and Cambridge Analytica.
"Honestly we thought we were acting perfectly appropriately, we thought we were doing something that was really normal."
"What happened was, they approached me," he said.
"In terms of the usage of Facebook data they wrote the terms of service for the app, they provided the legal advice that this was all appropriate."
But he said "one of the great mistakes I did here was I just didn't ask enough questions".
Mrs May was challenged in the Commons over the Tory party's links to CA's parent company SCL Group.
The SNP's Westminster leader Ian Blackford said the firm "has been run by a chairman of Oxford Conservative Association, its founding chairman was a former Conservative MP, a director appears to have donated over £700,000 to the Tory Party, a former Conservative Party treasurer is a shareholder".
The Prime Minister said that "as far as I am aware" there were no current Government contracts with CA or SCL.